Control-flow elements for a pipeline: steps that control the way their child-steps are being run.

DEPRECATED: Build-steps that let you work with git repositories.
Use the [`lambdacd-git` library](https://github.com/flosell/lambdacd-git) instead.

> (wait-for-manual-trigger args ctx) ; Blocks, but setting `:trigger-id` in step-result to a random UUID
> (post-id ctx trigger-id trigger-parameters) ; Returns immediately, unblocks the waiting manual trigger

Build step that waits for manual user interaction.

Example:
```clojure
> (wait-for-manual-trigger args ctx) ; Blocks, but setting `:trigger-id` in step-result to a random UUID
> (post-id ctx trigger-id trigger-parameters) ; Returns immediately, unblocks the waiting manual trigger
```

Build step to run scripts in a separate shell process. Needs `bash` to run.

Predicates over step status.

Functions that implement logic to summarize a list of statuses into a single status.
Commonly used in combination with `unify-only-status` as a `:unify-results-fn` to generate the status of a parent step from the statuses of child steps.
These functions might return `:unknown` if a combination of statuses does not make sense to their scenario.

(defn some-step [args ctx]
  (chaining args ctx
            (shell/bash injected-ctx "/ " "echo hello ")
            (shell/bash injected-ctx "/ " "echo world ")))

(defn some-step-with-error-handling [args ctx]
  (always-chaining args ctx
                   (run-tests injected-args injected-ctx)
                   (if (= :failure (:status injected-args))
                     (publish-test-failures injected-args injected-ctx))))

Functions that allow you to use LambdaCDs pipeline mechanisms inside a step, i.e. chain several steps together:

```clojure
(defn some-step [args ctx]
  (chaining args ctx
            (shell/bash injected-ctx "/ " "echo hello ")
            (shell/bash injected-ctx "/ " "echo world ")))

(defn some-step-with-error-handling [args ctx]
  (always-chaining args ctx
                   (run-tests injected-args injected-ctx)
                   (if (= :failure (:status injected-args))
                     (publish-test-failures injected-args injected-ctx))))
```

Functions that help in adding the ability for a step to be killed.

Functions that support build steps in dealing with metadata

Functions and macros that simplify dealing with a steps user readable output (`:out`). Two approaches are provided:
The _printer_ approach that gives full control over what will be provided as output and the `capture-output`-approach that just redirects all stdout.